Severe acute respiratory syndrome (SARS)
Severe acute respiratory syndrome (SARS) is a serious form of pneumonia, caused by a virus isolated in 2003. Infection with the SARS virus results in acute respiratory distress (severe breathing diffculty) and sometimes death. It is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a networked health system can respond to an emerging threat.
This contagious respiratory infection was first described on Feb. 26, 2003. SARS was identified as a new disease by World Health Organization (WHO) physician Dr. Carlo Urbani. He diagnosed it in a 48-year-old businessman who had traveled from the Guangdong province of China, through Hong Kong, to Hanoi, Vietnam. The businessman died from the illness. Dr. Urbani subsequently died from SARS on March 29, 2003, at the age of 46.
In the meantime, SARS was spreading, and within 6 weeks of its discovery, it had infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools had closed throughout Hong Kong and Singapore. National economies were affected.
The WHO had identified SARS as a global health threat, and issued an unprecedented travel advisory. Daily WHO updates tracked the spread of SARS seven days a week. It wasn't clear whether SARS would become a global pandemic, or would settle into a less aggressive pattern.
The rapid, global public health response helped to stem the spread of the virus, and by June 2003, the epidemic had subsided to the degree that on June 7 the WHO backed off from its daily reports. Nevertheless, even as the number of new cases dwindled, and travel advisories began to be lifted, the sober truth remained: every new case had the potential to spark another outbreak. SARS appears to be here to stay, and to have changed the way that the world responds to infectious diseases in the era of widespread international travel.
Causes, incidence, and risk factors
SARS is caused by a member of the coronavirus family (the same family that can cause the common cold).
When someone with SARS coughs or sneezes, infected droplets spray into the air. You can catch SARS if you breathe in or touch these particles. The SARS virus may live on hands, tissues, and other surfaces for up to 6 hours in these droplets and up to 3 hours after the droplets have dried.
While droplet transmission through close contact was responsible for most of the early cases of SARS, evidence began to mount that SARS might also spread by hands and other objects the droplets had touched. Airborne transmission was a real possibility in some cases. Live virus had even been found in the stool of people with SARS, where it has been shown to live for up to four days. And the virus may be able to live for months or years when the temperature is below freezing.
With other coronaviruses, re-infection (becoming infected and falling ill again) is common. Preliminary reports suggest that this may also be the case with SARS.
Symptoms usually occur about 2 to 10 days after coming in contact with the virus, although there have been some cases where the illness started considerably sooner or later. Those with active symptoms of illness are clearly contagious, but it is not known how long a person may be contagious before or after symptoms are present.
The hallmark symptoms are fever greater than 100.4 degrees F (38.0 degrees C) and cough, difficulty breathing, or other respiratory symptoms. Symptoms in the order of how commonly they appeared have included:
- Chills and shaking
- Muscle aches
Less common symptoms include (also in order):
- Productive cough (sputum)
- Sore throat
- Runny nose
- Nausea and vomiting
Signs and tests
Your health care provider may hear abnormal lung sounds while listening to the chest with a stethoscope. In most persons with SARS, worsening chest x-ray or chest CT changes show the presence of pneumonia or respiratory distress syndrome.
Tests tests used to diagnose SARS might include:
- Blood clotting tests
- Blood chemistries
- ALT and CPK are sometimes elevated.
- LDH levels are often elevated.
- Sodium and potassium are sometimes low.
- Chest x-ray or chest CT scan
- Complete blood count (CBC)
Much attention was given early in the outbreak to developing a quick, sensitive test for SARS. Specific tests include the PCR test for SARS virus, antibody tests for SARS, and direct SARS virus isolation. All current tests have some limitations.
Persons suspected of having SARS should be evaluated immediately by a health care provider, and hospitalized under isolation if they meet the definition of a suspected or probable case.
Treatment may include:
- Antibiotics to treat bacterial causes of atypical pneumonia
- Antiviral medications
- High doses of steroids to reduce lung inflammation
- Oxygen, breathing support (mechanical ventilation), or chest physiotherapy
In some serious cases, blood serum from people who have already recovered from SARS has been given. There is no strong evidence that these treatments work well.
As the first wave of SARS began to subside, the death rate proved to have been about 14 or 15 percent of those diagnosed. In people over age 65, the death rate was higher than 50 percent. Many more were sick enough to require mechanical ventilation. And more still were sick enough to require hospitalization in intensive care units.
Intensive public health policies are proving to be effective in controlling outbreaks. Many nations have stopped the epidemic within their own countries. All nations must be vigilant, however, to keep this disease under control. Viruses in the coronavirus family are known for their ability to change (mutate) in order to better spread among humans.
- Respiratory failure
- Liver failure
- Heart failure
Calling your health care provider
Call your health care provider if you suspect you or someone you have had close contact with has SARS.
Reducing your contact with someone with SARS lowers the risk for the disease. Ways to do this may include limiting travel to locations where there is an uncontrolled outbreak. When possible, avoid direct contact with persons who have SARS for at least 10 days after their fever and other symptoms are gone.
The U.S. Centers for Disease Control and Prevention (CDC) says hand hygiene is the most important part of SARS prevention. This might include hand washing or cleaning hands with an alcohol-based instant hand sanitizer.
Persons should be taught to cover the mouth and nose when sneezing or coughing. Respiratory secretions should be considered infectious, which means no sharing of food, drink, or utensils. Commonly touched surfaces can be cleaned with an EPA approved disinfectant.
In some situations, appropriate masks and goggles may be useful for preventing spread of the disease. Gloves might be used in handling potentially infectious secretions.
Vijayanand P, Wilkins E, Woodhead M. Severe acute respiratory syndrome (SARS): a review. Clin Med. 2004 Mar-Apr;4(2):152-60.
Ng EK, Lo YM. Molecular diagnosis of severe acute respiratory syndrome. Methods Mol Biol. 2006;336:163-75.
David A. Kaufman, M.D., Section Chief, Pulmonary, Critical Care & Sleep Medicine, Bridgeport Hospital-Yale New Haven Health System, and Assistant Clinical Professor, Yale University School of Medicine, New Haven, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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